Rosignano Marittimo is a comune (municipality) in the Province of Livorno in the Italian region Tuscany, located about 80 kilometres (50 miles) southwest of Florence and about 20 kilometres (12 mi) southeast of Livorno.

Rosignano Marittimo borders the following municipalities: Castellina Marittima, Cecina, Collesalvetti, Livorno, Orciano Pisano, Santa Luce.

The comune is formed by the municipal seat of Rosignano Marittimo and the frazioni – towns and villages – of Castelnuovo della Misericordia, Castiglioncello, Gabbro, Nibbiaia, Rosignano Solvay and Vada.

The resort town of La Mazzanta is also included in the municipality.

During World War II a major United States Army Air Force base was located near Rosignano, controlled by the Twelfth Air Force.